Treatment of dyspnea must be guided by assessment; however standard measures of dyspnea rely on self-report. Cognitive impairment and nearness to death may interfere with symptom distress reporting leading to under-recognition and over or under-treatment. Previous psychometric testing of the only known behavioral tool, the Respiratory Distress Observation Scale (RDOS), demonstrated internal consistency, construct validity with hypoxemia, convergent validity with dyspnea self-report and discriminant validity with pain and no dyspnea. The RDOS performed well when tested with terminally ill patients who were at risk for respiratory distress, most of whom could not self-report dyspnea. The tool is sensitive to detect changes over time and measure response to treatment. We do not know if the RDOS can be accurately scored by family caregivers; inter-rater reliability across members of the clinical team, including family caregivers, who may use the RDOS needs to be established. The cut-points to signify mild, moderate or severe distress also need to be determined. During a 2-year study interval we plan to seek patients who are seriously ill and at risk for dyspnea and conduct inter-rater reliability testing between a trained research RN and family caregivers. Additionally, at study enrollment, the patient will be asked to respond to a query about shortness of breath, indicate severity on a numeric rating scale (NRS) and assign a descriptor from among none, mild, moderate, or severe distress. Analysis of agreement on RDOS scoring among examiners will establish family caregiver inter-rater reliability and measurement invariance. Analysis of patient descriptors with NRS, verbal descriptors and RDOS will determine distress intensity cut-points. The results of this project will afford use of the RDOS as the major outcome to ascertain patient distress or comfort across care settings in future studies of patients who are near death and unable to provide a dyspnea self-report.